Electric Under Floor Heating

Electric Under Floor Heating Mats & Cables

What is ATC under floor heating cable?

ATC under floor cable heating mats are manufactured from twin conductor, thin profile (3mm), double insulated and earth braided heating cables attached to a 500mm open weave mat backing 70mm centres to produce a standard 160 watts square metre (w/m2) output.

What if I have a large area to heat?

Installations larger than 16.25M2 will require 2 heating mats or cables wired in parallel up to a maximum of 22.1M2. It is advisable to contact a qualified electrician for this type of installation.

Can ATC under floor heating cables be cut to length if floor too long?

Under no circumstances can under floor heating cables be cut to length. For single heating cables the floor spacing pitch can be adjusted closer together down to a minimum of 30mm, this will result in a higher wattage output per M2.

How quickly can I expect my tiled floor to get warm with ATC heating mats?

This depends on a number of factors like the sub-floor type and insulation: a cement sub-floor will be slow to warm without a thermal insulation barrier, creating a significant drag on the performance of the floor heating. A layer of high quality insulation (F-Board) will have a dramatic effect in these circumstances, speeding up the initial warm up time to within 15-20 minutes. We recommend the use of F-Board under floor heating insulation.

Will under floor cable heating also warm my room?

This will depend on the “u value” of your room. This is an industry term for the total measure of resistance of each component that make up the fabric of the building. Simply put, this means that old buildings will lose heat faster than modern buildings where the latest materials are incorporated. Under floor heating insulation will go a long way to
offsetting these drawbacks, helping to retain the heat within the room. Under floor cable heating acts like a large low level radiator gently heating the room from the floor up. It requires approximately 15% less energy to feel the same level of comfort experienced using convection heating.

Will under floor heating provide enough heat for my conservatory or bathroom?

With a good level of floor insulation and the correct choice of under floor heating cable to get the maximum coverage and output, then in most circumstances under floor heating will provide the required room temperature. Most conservatories are not required to pass any building regulations u value, so depending on the type of glass structure you have, supplemental heating may be required for odd occasions like cold winter nights.

Can I adjust the temperature of the floor heating mat?

Each under floor heating installation is controlled by programmable, digital thermostat. This will maintain your floor temperature and on/off times at a precise setting according to your own individual taste.

How can I control the under floor heating to come on and go off?

Each installation is controlled by a programmable, digital thermostat. This will look after your day to day, on and off requirements to your own individual settings.

Are there any special tools required for the under floor heating installation?

Tiling over under floor heating cables should always be done using a plastic trowel. Any damage by the sharp edge of a traditional steel trowel mat result in damage to the outer, protective jacket of the under tile heating cable, this could eventually result in a future failure of the under floor heating cable. The under floor heating system should be tested as per the warranty form enclosed with each mat to ensure it is correctly installed. This warranty form should be completed and returned to ATC.

Will I need an electrician to connect the under floor heating mat installation?

We always recommend a fully qualified electrician to install your under floor cable, the cable will need to be tested with specialised tools that usually only electricians have. If these tests are not carried out at the time of installation this will have an effect on the warranty .

Is there any special adhesive I need to use when fitting an under floor cable heating system?

Yes, a flexible floor tile adhesive will be required. The special polymers added to flexible adhesives will make allowances for any tile floor movements through heat expansion and contraction. Don’t forget to also add a flexible grout to your list.

Can I tile straight on top of the cable heating mats?

For heated cable mats, the heating cables are secure within the heating mat backing, the Tiller can commence with the flexible floor tile adhesive and tiling operation as soon as the under floor cable heating system is fitted and tested.

What extra height will the under floor cable heating mat add to my floor?

This will depend on the size of the cable heating mat and if insulation board is used but an allowance of an extra 4mm for cable mat and 6-10mm for insulation board, to your planned finished height is a reasonable figure.

What guarantee comes with the under floor cable heating mats?

All ATC under floor heating systems come with a 10 year manufacturer’s guarantee.

Can I install under floor cable heating mats under wood laminate flooring?

This is possible but we recommend using under floor heating film. Ask our technical department for more information. Please note these answers are very general please contact our Technical Department for more detailed information.

Please note these answers are very general please contact our Technical Department for more detailed information.

Electric Underfloor Heating – Thermal Insulation Board

Can I install the under floor cable heating mats without insulation?

Yes this is entirely possible but the 2nd law of thermodynamics shows us that heat will always be attracted towards cold: heat energy will dissipate in to the sub-floor, requiring more heat energy to bring the heated floor up to temperature.

How will insulation improve performance of my under floor cable heating?

A high quality thermal barrier will slow the process of heat loss into the sub-floor, significantly improving the performance, speeding the initial warm up times and reducing the electricity costs. We recommend F-Board under floor heating insulation.

What type of under floor heating insulation will give me the best all round performance?

Extruded polystyrene foams will give the best all round performance. Polystyrene has high thermal insulation properties, high compressive strength capable of supporting normal foot impact loading, waterproof, rot resistant, light weight, easy to handle, easily cut and shaped with a sharp knife, available in two depths, 6mm and 10mm and low cost. We recommend F-Board under floor heating insulation.

What is F-Board under floor heating insulation?

Fast warm under floor heating insulation boards are manufactured from extruded polystyrene foam, designed to meet the very specific needs of the under floor heating industry.

How strong are fast warm under floor heating insulation boards?

F-Board under floor heating insulation boards are designed to meet the very rigorous needs to be both high thermal value and high compressive strength, capable of normal foot traffic point loading. They cannot be used as a replacement for floor boards or plywood flooring.

What depth of under floor heating insulation do I need?

A simple rule of thumb is to incorporate as much heating insulation wherever possible. For new build projects this is easy to plan in a typical refurbish situation this is not always possible where the finished heated floor height may restrict the depth available to add the heating insulation. F-Board under floor heating insulation boards are available in 6mm and 10mm.

How do I fix fast warm under floor heating insulation boards to the sub-floor?

For cement sub-floors F-Board under floor heating insulation boards will readily bond to any good quality flexible, water based (solvent free) floor adhesive. For heated wood floors care must be taken to ensure that the floor is firmly fixed to the joists, following the recommended 300mm screwed centres as a guide, prior to applying the flexible floor tile adhesive and bonding the fast warm insulation boards.

Electric Under Floor Heating – Thermostats

Which thermostat to I need to use?

We offer 2 different types of thermostat for use with our underfloor heating; these are the OTN-1991H Analogue thermostat and the ICD3-1999 Digital thermostat.

The Analogue thermostat is used where there is no need to turn the underfloor heating system off during the day. It is a simple thermostat with an on/off switch and a dial for adjusting the temperature.

When you need to turn the heating system off during the day, the Digital thermostat is used to set the underfloor heating system to come on and off by using a built in time-clock. Up to 2 “on/off” settings per day can be programmed e.g. morning and afternoon.

The OCC2-comes pre-programmed to the following times:

Day 1-5 Event Time Temperature













Day 6-7 Event Time Temperature







Why do I need a Floor Sensor?

All of the thermostats that ATC offer measure the floor temperature to turn the underfloor heating system on and off. Because the thermostat measures the floor temperature is it much more accurate than measuring the air temperature. This means the system is more efficient and uses less electricity.

Both the OTN-1991H and the ICD3-1999 come complete with the ETF199 universal floor sensor. The floor sensor is installed in a 16mm flexible conduit under the floor tiles or laminate floor; this enables the sensor to be replaced in the unusual event of a failure or damage.

What does the flashing Error on the display of my ICD3-1999 mean?

The ICD3-1999 thermostat features a built in diagnostic mode to help you find out what is wrong with your underfloor heating system in the event of a failure. There are 2 codes that the thermostat will show “Internal Failure” & “External Failure”.

Internal Failure This means that the internal circuit board has failed and the thermostat needs to be replaced.

External Failure: This means that the external Floor Sensor is disconnected or has failed. This is the most often seen issue with the ICD3-1999 thermostat. It is usually caused by the incorrect connection of the heating mat and sensor cables. This error can be easily fixed by your installer by checking to make sure the sensor cable is wired into the last 2 terminals on the back to the thermostat and that the heating mat is connected into terminals 3 and 4. Your installer can also check the floor sensor and heating mat resistance in the table below to identify what the cables are.

Code Mat Size (m2) Output (W) Current Draw(A) ±10% Resistance (Ω) ±10%
LDTS160/0.5 0.5 80 0.35 661
LDTS160/1 1 160 0.70 331
LDTS160/1.5 1.5 240 1.04 220
LDTS160/2 2 320 1.39 165
LDTS160/2.5 2.5 400 1.74 132
LDTS160/3 3 500 2.17 106
LDTS160/3.5 3.5 560 2.43 95
LDTS160/4 4 640 2.78 83
LDTS160/5 5 800 3.47 66
LDTS160/6 6 960 4.17 55
LDTS121210 7.6 1210 5.26 44
LDTS121400 8.8 1400 6.09 38
LDTS121800 11 1740 7.57 30
LDTS122150 13.3 2150 9.35 25
LDTS122600 16.25 2600 11.30 20
ETF-199 Floor sensor N.T.C 12k resistance table
-20°C = 112246Ω 11°C = 22300Ω 16°C = 17750Ω 21°C = 14238Ω 26°C = 11506Ω 35°C = 7978Ω 60°C = 3201Ω
-10°C = 63929Ω 12°C = 21292Ω 17°C = 16974Ω 22°C = 13636Ω 27°C = 11035Ω 40°C = 6569Ω 70°C = 2306Ω
0°C = 37942Ω 13°C = 20335Ω 18°C = 16237Ω 23°C = 13064Ω 28°C = 10587Ω 45°C = 5442Ω 80°C = 1692Ω
5°C = 29645Ω 14°C = 19428Ω 19°C = 15537Ω 24°C = 12519Ω 29°C = 10159Ω 50°C = 4535Ω 90°C = 1263Ω
10°C = 23364Ω 15°C = 18567Ω 20°C = 14871Ω 25°C = 12000Ω 30°C = 9752Ω 55°C = 3800Ω 100°C = 958Ω